A typical production well has a metal lining, or casing, that extends through the well. A series of perforations are made at specific depths in the casing. The perforations enable fluids in the strata surrounding the perforations to flow into the casing, while preventing fluids at other depths from flowing into the casing. The fluids are then removed from the well through the interior of the casing, either by the pressure of the fluid in the formation or by artificially lifting the fluid to a collection location.
A typical oil or gas production well may pass through many different formations, or strata. The various strata may contain oil, gas, water, or combinations thereof. Preferably, the perforations in the casing are made at depths that correspond to strata bearing a desired production fluid, such as oil and/or natural gas, and minimal amounts, if any, of water. However, the fluid flowing into the interior of the casing may contain portions of oil, gas, and water. Additionally, the proportions of oil, gas, and/or water that enter through the perforations from the surrounding strata may vary according to depth.
Consequently, some wells are profiled to identify the proportions of water, oil, and gas flowing into the casing at various depths. An iterative process of plugging and logging the well is used to form the profile of the well. First, a plug is lowered into the well by an insertion device to isolate a portion of the well. The insertion device is then removed from the well and a logging tool is lowered into the well. An artificial lift system, such as a pump, is used to produce a flow of fluid into the casing through a first group of perforations. The logging tool is operable to detect characteristics of the fluid entering the well, such as the proportion of oil, gas, and water flowing into the casing.
To detect the characteristics of the fluid entering the well through a second group of perforations, the logging tool is removed from the well and the insertion device is lowered back into the casing to move the plug to a second location. The logging tool is then lowered back into the well to log the fluid characteristics through the second group of perforations. This process may be repeated for many groups of perforations. By analyzing the data, those groups of perforations that do not produce desired production fluids and/or produce large amounts of water may be isolated using a plug, or other device.
The iterative process described above is time-consuming and labor intensive. A need exists for a system or method that enables a well to be profiled without having to repeatedly remove the logging tool and/or insertion device from the well.